Comparison between time integrated sampling and direct reading sampling of nanoparticulate at the workplace

Abstract

Objective: Nanoparticles are generated by engineered and unintended in a variety of workplaces and process. Nanoparticles generation in unintended nanoparticle emitting workplace may originate from hot process, welding process. Number and surface area concentration of nanoparticles is generally assessed by a variety of direct reading instruments unlike traditional method. The purposes of this study were to compare time integrated sampling and direct reading instrument sampling method at nanoparticles generation workplaces, and to compare statistically full time sampling and time interval sampling categorized by time integrated sampling method. As characteristics of a variety of workplaces measured in this study were investigated, this study suggests appropriate sampling method by workplace. Methods: Sampling was used two methods

the way to use a filter which sampled the air of workplace as time integrated sapling method and the way to sample by direct reading instrument such as SMPS, DustTrak, AeroTrak. Each filter was measured the direct reading instrument simultaneously, and for full time sampling compared with time interval, time interval sampling is measured for working time while replacing a filter by predetermined time interval. Analysis is performed for mass, metals, and TEM. Statistical analysis is performed to compare associations between metrics. Results: Concentrations measured at unintended nanoparticle emitting workplaces were higher than those at engineered nanoparticle manufacturing workplaces. CV of concentration is larger as shorter time interval. Full time samples were significantly higher coefficient than time interval samples in spearmans rank test. Conclusions: As PM2.5 concentration out of total mass concentration measured at welding workplaces was above 90%, mass concentration is recommended by gravimetric method. Although concentration measured at engineered nanoparticle manufacturing workplaces was relatively low, nanoparticles generation ratio is high. Therefore, the best way of sampling methods are recommended by using together direct reading instrument and gravimetric sampling method.